SEYNE-LES-ALPES, France — Investigators have extracted audio from one of the black boxes of the German jetliner that crashed in the Alps, but they warned on Wednesday that analyzing it could take weeks.
Remy Jouty, director of France’s aviation investigation agency, told reporters that it was too soon to draw conclusions about why the plane went down, killing all 150 people on board, on a routine flight from Barcelona to Dusseldorf, Germany.
“We just succeeded in getting an audio file which contains usable sounds and voices,” he said. "We hope to have a first rough idea in a matter of days, and having a full understanding ... will take weeks and even months.”
He did say that there was no midair explosion, and that the plane “flew to its end.” But he said investigators do not have a hypothesis on why the plane, Germanwings Flight 9525, began its eight-minute descent from cruising altitude and crashed.
The crash left remnants of the plane scattered all over the mountainside. The remote, rugged terrain has posed an enormous challenge for investigators.
“It’s very difficult to see this because there’s a lot of little pieces,” Xavier Roy, the French civil aviation coordinator, told NBC News in an interview. “We cannot find a cockpit or big pieces, so it’s very difficult to see.”
Among the dead were at least three Americans. NBC News confirmed that Yvonne Selke and her daughter Emily, from Virginia, were killed in the crash. The State Department said later that a third American, whom it did not identify, was also killed.
The audio was extracted from the mangled cockpit voice recorder, one of the two so-called black boxes on the Airbus A320. President Francois Hollande said that the frame of the flight data recorder had been recovered, but not the device itself.
Photo Gallery: Crews Continue Search of Remote Crash Site
Lufthansa, which owns Germanwings, said that repairs were conducted on Monday on the hatch through which the nose wheel descends before landing. A spokeswoman said the repairs were to reduce noise, not a safety issue. The plane was in service for 24 years.
Some Germanwings crew members have refused to fly following the accident.
French Interior Minister Bernard Cazeneuve acknowledged that all possible explanations for the crash are being considered, but told RTL radio that terrorist action is not the most likely theory.
Officials confirmed to NBC News that the French air force had scrambled a Mirage fighter jet to the area when the Germanwings flight lost radar contact on Tuesday, but the jet arrived too late and didn't spot the wreckage.
Hollande and German Chancellor Angela Merkel visited the crash site on Wednesday, where recovery efforts had been underway since daybreak over the scattered debris field.
Roy said that searchers had to be lowered to the crash site from helicopters. No bodies had been recovered, he said.
"There are no wings. No cockpit. Nothing," Roy said. "I have never seen anything like it before."
The aircraft was traveling at 430 mph when it crashed and its impact was "very hard," according to Jean-Paul Troadec, former head of France's Bureau of Investigation for Aviation.
His account was echoed by Cazeneuve’s spokesman, Pierre-Henry Brandet, who told NBC News that those who had flown over the site “can't even identify anything that looks like a plane.”
“We will take all the time necessary” to remove the victims, he added.
Grieving families were also expected to arrive at the scene and Lufthansa said it would help transport relatives to the site.
"We have not been able to contact all of the relatives yet," Germanwings Managing Director Thomas Winkelman told reporters.
The victims included two babies, two opera singers, an Australian mother and her adult son vacationing together, and 16 German high schoolers returning with their teachers from an exchange trip to Spain.
In Seyne-les-Alpes, locals had offered to host bereaved families because of a shortage of rooms to rent, said the town's mayor, Francis Hermitte.
Claude Buzon, 67, who lives in a village near the crash site, said the doomed plane made a "low sound" unlike the noise normally made by passing jets. "Afterwards I heard no explosion, no impact, nothing," he said.
"It is inexplicable this could happen to a plane free of technical problems and with an experienced, Lufthansa-trained pilot," Lufthansa CEO Carsten Spohr told reporters in Frankfurt.
In Spain, flags flew at half-staff on government buildings and a minute of silence was held in government offices across the country. Parliament canceled its normal Wednesday session.
Germanwings workers at the company's Cologne headquarters and at several airports observed a one-minute silence to mark the tragedy at 10:53 a.m. local time, the moment the airline says the plane crashed.
Lufthansa — whose employees worldwide also observed a moment of silence — said the flight number 4U9525 had been retired.
NBC News' Nancy Ing, Carol Marquis and Zainab Abdul Aziz and The Associated Press contributed to this report